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Sixth Catalogue of Fundamental Stars (FK6). Part III. Additional fundamental stars with direct solutions
The FK6 is a suitable combination of the results of the HIPPARCOSastrometry satellite with ground-based data, measured over a longinterval of time and summarized mainly in the FK5. Part III of the FK6(abbreviated FK6(III)) contains additional fundamental stars with directsolutions. Such direct solutions are appropriate for single stars or forobjects which can be treated like single stars. Part III of the FK6contains in total 3272 stars. Their ground-based data stem from thebright extension of the FK5 (735 stars), from the catalogue of remainingSup stars (RSup, 732 stars), and from the faint extension of the FK5(1805 stars). From the 3272 stars in Part III, we have selected 1928objects as "astrometrically excellent stars", since their instantaneousproper motions and their mean (time-averaged) ones do not differsignificantly. Hence most of the astrometrically excellent stars arewell-behaving "single-star candidates" with good astrometric data. Thesestars are most suited for high-precision astrometry. On the other hand,354 of the stars in Part III are Δμ binaries in the sense ofWielen et al. (1999). Many of them are newly discovered probablebinaries with no other hitherto known indication of binarity. The FK6gives, besides the classical "single-star mode" solutions (SI mode),other solutions which take into account the fact that hidden astrometricbinaries among "apparently single-stars" introduce sizable "cosmicerrors" into the quasi-instantaneously measured HIPPARCOS proper motionsand positions. The FK6 gives, in addition to the SI mode, the "long-termprediction (LTP) mode" and the "short-term prediction (STP) mode". TheseLTP and STP modes are on average the most precise solutions forapparently single stars, depending on the epoch difference with respectto the HIPPARCOS epoch of about 1991. The typical mean error of anFK6(III) proper motion in the single-star mode is 0.59 mas/year. This isa factor of 1.34 better than the typical HIPPARCOS errors for thesestars of 0.79 mas/year. In the long-term prediction mode, in whichcosmic errors are taken into account, the FK6(III) proper motions have atypical mean error of 0.93 mas/year, which is by a factor of about 2better than the corresponding error for the HIPPARCOS values of 1.83mas/year (cosmic errors included).
| VBLUW photometry of fifteen alpha CYG variables (including LBVs) in the Galaxy, the LMC and the SMC
VBLUW photometry (Walraven system) of 15 alpha Cyg-type variables,(luminous massive stars), including 10 LBVs and one suspected LBV arepresented. Formulae are given to transform the V and V-B of the Walravensystem to V and B-V of the Johnson UBV system.
| UBVRI photometry of the FK5 Extension Catalogue Stars
UBVRI photometry in the Kron-Cousins system for 272 stars of theExtension Catalogue of the Fifth Fundamental Star Catalogue (FK5 stars)in the declination zone +7 deg to -90 deg is presented. Tables 1-2 arealso available in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html Based on observations made atthe European Southern Observatory, La Silla, Chile.
| Cyclicities in the light variations of LBVs. I. The multi-periodic behaviour of the LBV candidate ζ^1^ Sco.
Differential Stroemgren uvby photometry of ζ^1^ Sco collectedduring the time interval 1982-1995 is analysed together with new VBLUWphotometry with a complementary discussion of unpublished JHKLM data. Wereport the discovery of a ~1750-2200d regular oscillation of amplitude~0.01mag in all bands, and pulsation-like oscillations with at least onefrequency f_1_=0.03155 (P~32days) and a possible second frequencyf_2_~5/4 f_1_ ~0.03891 (P~25.7 days). Most likely, all such starsexhibit multi-periodic light variability. A strong noise componentremaining in the prewhitened signal leads us to postulate that thedriver for LBV-like eruptions is stochastic resonance. This hypothesisis supported by the historic light curve of ζ^1^ Sco which showsthat two centuries ago the star was about 2 magnitudes brighter, while amillenium ago it was only 1 magnitude brighter than today, an indicationthat ζ^1^ Sco should be regarded as a candidate Luminous BlueVariable.
| The position corrections of 1400 stars observed with PA II in San Juan.
Not Available
| Fifth fundamental catalogue. Part 2: The FK5 extension - new fundamental stars
The mean positions and proper motions for 3117 new fundamental starsessentially in the magnitude range about 4.5 to 9.5 are given in thisFK5 extension. Mean apparent visual magnitude is 7.2 and is on average2.5 magnitudes fainter then the basic FK5 which has a mean magnitude of4.7. (The basic FK5 gives the mean positions and proper motions for theclassical 1535 fundamental stars). The following are discussed: theobservational material, reduction of observations, star selection, andthe system for the FK5 extension. An explanation and description of thecatalog are given. The catalog of 3117 fundamental stars for the equinoxand epoch J2000.0 and B1950.0 is presented. The parallaxes and radialvelocities for 22 extension stars with large forecasting effects aregiven. Catalogs used in the compilation of the FK5 fundamental catalogare listed.
| Light variations of massive stars (Alpha Cygni variables). IX
High-precision VBLUW photometry of 22 highly luminous OBA-type stars, 13of which are Alpha Cygni variables and two of which are variable only incolor, is presented. It is suggested that sigma (V-B) increases fasterthan sigma (B-L) with later spectral types due to the absence ofstochastic metal line strength variations in the V band. It is assumedthat short-time-scale stellar spot activity is present, or thattemperature and density waves move through the atmospheres with the sametime scales, producing these line strength variations independent of thecontinuum variations. The possibility of differentiating stars which lieclose to each other in the HR diagram but have different evolutionaryhistories (and thus different metal abundances) with the aid of themaximum light amplitude/sigma (V-B) diagram is considered.
| An investigation of the micro variations of highly luminous OBA type stars. IV
VBLUW photometry of eight OBA type stars of high luminosity, M(001) lessthan -7, is presented. The mean errors of the nightly averages amount toless than or equal to + or - 0.002 mag. All but presumably one appear tobe variable, of which the maximum light amplitude amounts up toapproximately 0.1 mag. The variability of brightness and colors, andtheir time scales (days to weeks) increase with decreasing temperature.
| Determination of proper motions in the region of the association Scorpius OB1
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Observation and Astrometry data
| Constellation: | Scorpius |
| Right ascension: | 16h58m23.60s |
| Declination: | -43°00'17.7" |
| Apparent magnitude: | 8.701 |
| Distance: | 293.255 parsecs |
| Proper motion RA: | 3.2 |
| Proper motion Dec: | -7 |
| B-T magnitude: | 9.006 |
| V-T magnitude: | 8.727 |
Catalogs and designations:
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